Compilare: user.cpp: In function ‘int main()’: user.cpp:43:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dictree.in","r",stdin); ^ user.cpp:44:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dictree.out","w",stdout); ^ user.cpp:45:15: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:46:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] if (n>0) scanf("\n"); ^ user.cpp:49:14: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s+1); l=strlen(s+1); ^ /tmp/ccIAzhbD.o: In function `main': user.cpp:(.text.startup+0xed): warning: the `gets' function is dangerous and should not be used.